I finished it last year on a 33lb 2006 Heckler with Fox Van 36's and very fat tyres. There were maybe a couple of bikes that were near to this weight (a burly Orange 5 and Turner mentioned above) but I definately felt very over biked, looking around at the start!
It was hard work (on the ups anyway!). Not convinced it was much of an advantage on the downs TBH.
I will lighten it up by a few lbs for next year (forks, tyres and wheels), as I cant afford another bike at the mo but I think if I could choose any bike, then it would prob be a Spark or an Anthem.
A hardtail would prob be quickest if you are a light rider who can cope with the fatigue a hardtail brings.